Field of the Invention
The present invention relates to an optical element for controlling light emitted from a light-emitting device.
Discussion of Related Art
The liquid crystal displays (LCDs) are devices in which electrical data generated from various devices are converted into visual data and transferred using the variation of liquid crystal transmittance according to the applied voltage.
The LCD, which does not have self light-emitting, provides backlight units (BLUs) which are light-emitting devices providing light on the back face of the liquid crystal panel on which images are displayed.
The BLU may be classified into an edge type and a direct type according to locations of the light-emitting diodes (LEDs) which are light sources.
In the edge type BLU, the LEDs which are the light sources are disposed on side faces of the light guide plate, and the light guide plate guides light emitted from the LEDs toward the liquid crystal panel through the total reflection, etc.
In the direct type BLU, the diffusion plate is used instead of the light guide plate, and the LEDs are disposed on the back face of the liquid crystal panel. Therefore, the LEDs emit light toward the back face of the liquid crystal panel.
Meanwhile, illumination uniformity in the LCD is an importance factor in determining the quality of the LCD, and to this end, the BLU should uniformly emits the light toward the liquid crystal panel.